Universe for high school students

The most incomprehensible thing about the
Universe is that; it is comprehensible.
- Albert Einstein
The Universe is comprehensible because it is
governed by scientific laws; that is to say, its
behaviour can be modelled.
- Stephen Hawking

Part -I
• How and Where did the Universe come
from and what awaits its final fate.
Part –II
• Human Journey in understanding Universe
since last 3000 years

Part –I
How and where did the UniverseUniverse come
from and what awaits its final fate.

The Magnitude of our Universe

The earth
Diameter at the equator - 7,930 miles
Av distance to the Sun - 93 million miles(1AU)
Average Density - 5.52 g per cu cm
Mass (M⊕) - 5.9722 x 1024
kg

The Sun
• Diameter at the equator - 864,000 miles
•
• Average Temperature - 5,500° C
• Temperature at core - 15,000,000 ° C
• Mass - 332,900 M⊕
• Density - 1.4 g per cu cm

Solar system
Planets
and their satellites,
asteroids and other rocky
objects, and an incalculable number
of comet like objects, some more
than 1 trillion miles from the Sun,
make up the solar system.

Our Sun with its Neighbours
There are Stars in our
Galaxy more than two
thousand times the
diameter of Sun

Our galaxy – milky way
• Diameter - 100,000 Light years
• Thickness - 1,000 Light years
• Stars it contains > 100,000,000,000 (100 bn)
• Mass - 1.5x1021
M⊕
(1 Light Year = 10 trillion km (1x1013
km )

Our UniverseOur Universe

Our universe
• Came into existence – 13.7 bn years ago
• Diameter – 46,600,000,000 (46.6 bn) light years.
• Galaxies it contains > 100,000,000,000 (100 bn)
• Stars it Contains > 100,000,000,000,000,000,000

What universe consist of
The universe
is everything that
exists, from the smallest
Particles to the largest ones,
together with all matter and energy.
The universe includes visible and invisible
things.

What universe consist of
The universe,
marvellous in its
majesty, is an ensemble
of > 100 billion galaxies. Each
of these galaxies (which tend to be
found in large groups) has 100 billion stars.
These galactic concentrations surround
empty spaces, called cosmic voids.

Where did this Universe come from ?

Big Bang
• Time: Zero Temperature: Infinite
• Size : Infinitesimal
Though we now know about the
Universe from a billionth of a second
after big bang, We do not know
much about the very moment of big
bang.

Big Bang
• Time: 10-43
sec Temperature: 1032 o
C
Universe's inflation begin

Expansion
Time: 10-38
C
universe
Increases in size
more than a trillion,
trillion, trillion times every
fraction of a second. The expansion
of the universe and the division of its forces
begin.

Forces appear
Time: 10-12
C
Gravity,
electromagnetic
force, strong nuclear force
and weak nuclear force appear.

Protons and Neutrons Appear
Time: 10-4
C
Protons and neutrons
appear, formed by three
quarks apiece. Light is trapped within
the web of particles, the Universe is still
dark

Dark mater
Time: 1 sec Temperature: 1010 o
C
The neutrinos
separate from the initial
particle through the disintegration
of neutrons. Though having extremely little
mass, the neutrinos might be the greatest
part of the universe's dark matter

Atom
C
The electrons
and their antiparticles,
positrons, annihilate each other until the
positrons disappear. The remaining
electrons form atoms in company with
proton.

Elements Form
C
The nuclei
of the lightest
elements, Hydrogen and
Thereafter Helium, form. Protons and
neutrons unite to form the nuclei of atoms

Light Escapes
Time: 380,000 Yrs Temperature: 2700o
C
Photons (particles of light)
escapes from the Dense Web of
particles and could now pass freely
through the Universe.

GRAVITATION GIVES SHAPE TO STARS

Galaxies
Time: 500 million yrs Temp: -243o
C
Galaxies
acquire their definitive
shape. Gravitation gives shape
to islands of millions and millions of
stars from masses of gases . The stars
explode as supernovas and disperse
heavier elements, such as carbon.

Solar system
Time: 9 Billion Yrs Temperature: -258o
C
Solar system
emerged. A mass of gas
and dust of supernova collapsed until it
gave rise to the Sun. Later the planetary
system was formed from the leftover
material.

Solar system
Time: 9.1 Billion Yrs Temp: -265o
C
Like the rest
of the planets, the Earth
formed of material that remained
After the formation of the solar system.

Expansion Continues
Time: 13.7 Billion Yrs Temp: -270o
C
Universe continues
to expand. Temperature near
big bang has cooled to 2.7 deg K

What awaits The future of
universe ?

Future of Sun
(and other stars up to 08 Solar Mass)
After five billion years
Supply of hydrogen will be exhausted,
and will transform into a red giant,
expanding
until it swallows Mercury. At its maximum size,
it
may even envelop the Earth and condenses
into a white dwarf.

The star swells
and heats up. The
heavy core of iron explodes as
SUPERNOVA and its dense core turns into a
NEUTRON STAR.
Future of other Stars
( more than 8 solar masses)

When the fusion
energy is unable to balance
its intense gravitational force
BLACK HOLE is formed, Its gravitation
captures even light.
Future of other Stars
( more than 20 solar masses)

Future of Stars
In the scale of
hundreds of billion years
all the stars in the universe will
flicker out after their nuclear fuel is
exhausted.

Future of Matter
1032
years.
Atoms disintegrate,
Protons and neutrons decay,
electrons and neutrinos separate.

Future of Universe
The big bang Theory
helped solve the enigma of the
early moments of the universe. What is yet
to be resolved is the mystery surrounding its
future.

The Mystery
To unravel this
mystery, the total mass
of the universe must be known, but
that figure has not been reliably determined.

Critical Density
For the universe
to reverse expansion,
An average density of more
than 10-29
gm /cm3
is required

Open Universe
It appears
that the mass of the
universe is far too little to stop
its expansion. If this is the case, the
universe's present growth is merely the last
step
before its total death in complete darkness.
Universe dies as temperatures in the entire
universe drops to near absolute zero.

Closed Universe
If the universe
had more than critical
mass, it would expand until reaching
a point where gravity stopped the expansion.
Big Crunch,
will culminate in
an infinitely small, dense, and hot spot
similar to the one from which the
universe was formed

Part –II
Human Journey in understanding Universe
since last 3000 years

If I have seen farther than most, it is because
I have stood on the shoulders of giants.
- Isaac Newton

At about 1000 BC people
believed:
• Stars were bonfires lit by other tribes in the
sky.
• Universe was a flat plate resting on the shell
of a giant turtle.
• Later, Egyptians thought that the Sun was a
ball of fire, and they had no idea what the
fuel was.

Understanding Universe
• 640 BC Greek philosopher Thales Named as the
world’s first mathematician predicted solar eclipse
accurately.
• 450 BC - The beginning of Physics Democritus said:
– Nothing exists except Atoms and Empty Space,
– Everything existing in the Universe is the result of
chance and necessity.
• 350 BC - Greek philosopher Aristotle
– Believed earth was a sphere and not a flat plate.
– Believed universe existed and would exist forever.
• Philosopher Anaxagoras Thought that the Sun was
a red hot iron.

• 300 BC Euclid Postulated laws of Geometry
• 212 .B.C.Eratosthenes Measured the
circumference of earth.
• Philosopher Thales – Water is the primary and
ultimate element

• Philosopher Anaximander – There exist primary
building block of matter but it can’t be water.
• Philosopher Parmenides – Matter can neither
come nor pass away.
• Philosopher Empedocles – There are only few
basic ingredients in the Universe, and everything
is combination in a multitude of ways.

• 2nd
Century AD- Ptolemy Thought the planets
orbited around Earth.
• 1514- Copernicus
– Put the Sun in the centre and planets
around it.
– Stars are fixed in its position, meaning a
static universe
• Johannes Kepler
– That planets orbit is not circular but elliptical.
– Formulated laws of planetary motion

• 1580s- Galileo Galilee.
• First to aim a telescope skyward.
• Developed the formula used to calculate the
free fall of any object toward earth.
• Relation between distance between distance,
time and speed.
• Object under free fall, fall faster over time and
the acceleration is constant.
• Free fall object irrespective of its weight touches
the ground at the same time.
• Concluded that object under motion will neither
slow down or speed up but
continue for ever. Thus contradicting
Aristotle’s belief that the object’s natural
state is rest.

• 1676- Ole Christensen Roemer Discovered
that light travels at a finite but very high speed.
•

• 1687- NEWTON'S EQUATION
– Formulated mathematical relation for
gravitational force between masses.
F = G m1x m2
r2
– Was the father of “infinitesimal calculus”

– 1700 – Galvani Invented battery.
– 1781- Philosopher Immanuel Kant Argued
that universe had a beginning.
– 1808 – John Dalton Declared that the basic
unit of chemical element is atom and each
chemical atom has its own weight.
– 1815- William Prout – All matters are made
up of Hydrogen.

Understanding universe
• 1800 – Scientists realised that Sun could not
have stayed hot for a long time had it been a
hot iron.
• 1809 - AstronomerJean Baptiste Joseph
Delambre Reported the time for light to travel
from the Sun to the Earth as 8 minutes and 12
seconds
• Around the same time Darwin pointed out
that the earth had to be hundreds of millions
year old.

– 1820- Hans Christian Discovered a connection
between electricity and magnetism.
– 1820’s –Ampere Found the mathematical
relation between electricity and magnetic field.
– 1823 – Philosopher Heinrich Olbers
Stars were not been shining for ever, but was
turned on in a finite past.
– 1830 – Michael Faraday
• Made laws of electrolysis.
• Invented electric motor.

• ..
1867 - Dmitri Mendeleev
Created the first Periodic Table of elements.

– 1850 – John Waterston A School teacher.
Showed that chemical energy could have
fuelled Sun only for some 10,000 years.
– 1853 - John Waterston Proposed that the Sun is
falling under its own weight and producing
heat.
– 1860 – William Thomson Calculated the Sun’s
age as 100 million with the idea of shrinking Sun.
– 1860 – James Clerk Maxwell Established
existence of electromagnetic waves moving
through space at a finite velocity of 3 x 10 8
m/s.

• 1865- James Clerk Maxwell Described the
theories of electricity and magnetism.
• 1874 – George Johnston Stony Coined the term
“Electron
• 1887-Albert Michelson Discovered that light traveled
at same speed irrespective of the speed and
direction of the one who measures it.
• 1887-1905- Dutch Physicist Hendrik Lorentz
Attempted to explain object contracting and clocks
slowing down when they move through ‘ether’ or
empty space.

– 1895 – Rontgen Accidentally discovered X-Rays.
– 1986 – Henri Becquerel Discovers radioactivity.
– 1896 – Marie and Pierre Curie Discovered release
of energy associated with radioactivity
– 1897 – William Thomson Refined his calculation
and said Sun was 25 million years old.
– 1897 – JJ Thomson Discovered that atoms have
inner structure, they contain electron.
– 1897 – Earnest Rutherford Unravelled atomic
structure and radioactivity.

– 1900- German scientist Max Plank Light
and other waves energy emission is in
packets called ‘quanta’ and not in any
arbitrary rate.
– 1904 - Ernest Rutherford Realized that
radioactivity could a source of energy for
Sun.

1905 – Albert Einstein
–Explained photo electric effect
–Formulated Theory of Special
Relativity, with that came E=Mc2

Einstein’s Relation. 1905-1915
Special Relativity Between Time-Space Time can beat at
different rates, depending on how fast one is moving. It means
that the speed of light appeared same for all observers.
Relativity Principle Between Mater-energy Energy and mass are
interchangeable, to be precise at E=MCE=MC22
. If an object
increases its mass, its energy increases, and vice versa. i.e.
mater is condensed energy.
Equivalence Principle Between Acceleration-Gravity law of
nature in an accelerating frame are equivalent to the laws in
a gravitational field. Gravity, according to this theory, is a
distortion of space that determines whether one object rolls
toward another.
General Relativity Between Mater-Energy and Time-Space The
presence of mater-energy determines the curvature of the
space-time surrounding it. Gravity is a result of this curvature.

• 1910 – JJ Thomson Demonstrated the
existence of Electron.
• 1911 – Ernest Rutherford Showed that atoms
are made-up of positive charged Nucleus
around which Electrons orbit.
• 1913 – Rutherford Stated that the enormous
temperatures Sun could make elements
change from one to another, which might
be stable on earth.

• 1920 – Francis Aston Found that the atomic
mass of Helium was one part in 120 less than
four Hydrogen atom.
• 1920 -Satyendra Nath Bose Laid the
foundation for new quantum mechanics of
Schrodinger, Heisenberg.
• 1920 – Sir Arthur Erdington Stated that Sun
burns Hydrogen into Helium producing heat
and light.
• 1939 – Hans Bethe Explained “CNO” cycle
responsible for Sun’s energy production.

• 1926- Werner Heisenberg Formulated uncertainty principle, by
which
– to predict a future position and velocity of a particle, one
should be able to measure present position and velocity.
– It is impossible to predict the position and velocity of a
particle in space,
– More precisely one parameter is measured, less precisely the
other can be measured.
• 1930 – Wolfgang Pauli Postulated that beta decay has to be
associated with emission of a particle with trifling mass.
• 1930 – Subramaniam Chandrashekar Discovered the
limiting mass of the star in formation of white dwarf and
neutron star.
• 1932 – James Chadwick Discovered that the nucleus contained
another particle called the Neutron which has almost same mass
of a proton but no electric charge.

Edwin Hubble
in 1929 observed that
the universe is expanding.
Which means at some point of
time earlier all matter was at one
point and its density was infinite. This
discovery brought the question of the
beginning of the universe into the realm
of science.

• 1940s, George Gamow Developed the
idea that the universe began with a
primordial explosion.
• 1960s- Arno Penzias and Robert Wilson
Accidentally detected A consequence of
Big Bang in existence of uniform
background radiation in space.
• 1960. Peter Higgs -predicts the existence of
a new particle, the Higgs boson.

• 1969 – Murray Gell-Mann Discovered
Particle elementary than proton and
neutron namely QUARK.
• 1970 – Scientists briefly contemplated if
the Sun was still shining, which was quickly
falsified.
• 1970-2000 – Standard model of ‘Particle
Physics’ contributed by many physicsts.
• 1998 - Saul Perlmutter, Brian Schmidt,
and Adam Riess discovered accelerating
expansion of the Universe

Understanding Space and Time

– Aristotle
•Stared that, there is a absolute position inStared that, there is a absolute position in
spacespace..
– Newton – There is no absolute state of rest.
•Stated that, it cannot be determined if twoStated that, it cannot be determined if two
events took place in different times occurredevents took place in different times occurred
in the same position.in the same position.
– Both Aristotle and Newton believed in absolute
time.
•Agreed that, one can unambiguouslyAgreed that, one can unambiguously
measure the interval of time between twomeasure the interval of time between two
events in space, and the time would be sameevents in space, and the time would be same
whoever measures it,whoever measures it, (provided they used a(provided they used a
good clock)good clock)

– Maxwell – Light should travel at fixed
speed.
– Albert Michelson Light travels at
same speed irrespective of the speed
and direction of the one who
measures it.
– Hendrik Lorentz Object contracts
and clocks slow down when they
move through ‘ether’.

• Einstein– Abandoned the idea of ‘ether’
and absolute time to explain the speed
of light.
– It means that the speed of light appearedIt means that the speed of light appeared
same for all observers.same for all observers.
– The energy the object has due to motion willThe energy the object has due to motion will
add to its massadd to its mass

The Consequence of Einstein’s Relativity.
– If a pulse of light is sent from one place to other.
– All observers will agree on the time for the
journey.
– All observers will not agree on the distance
– Since speed of light is the distance
travelled/time taken.
– As per relativity speed of light is same for all
observers.
– So, now all observers must disagree over the
time taken.
– Thus the theory of relativity put an end to
absolute time.

I am finished with Space and
Time for now

We each exist for but a short time, and in that time
explore but a small part of the whole Universe. We
wonder, we seek answers living in the vast world that is
by turn kind and cruel, and gazing at the immense
heavens above, people have always asked multitude of
questions: How can we understand the world in which
we find ourselves? How does the Universe behave?
What is the nature of reality? Where did all this come
from? Did the Universe need a creator? Most of us do
not spend most of our time worrying about these
questions. But almost all of us think about them some
time or other.

- Stephen Hawking
82
QuoteQuote

• Hyper Space – by Michio Kaku
• A Brief History of Time – by Stephen Hawking
• Articles on Astrophysics from Encyclopedia Wikipedia
• Illustrated Science Library – Britannica
• The God Particle - Leon M. Lederman
• The Grand Design - Stephen Hawking
• Euclid’s Widow - by Leonard Mlodinow
• The Human Touch – by Michael Frayn
• Absolutely Small - Michael D Frayer
• Public lectures and colloquium of Prof Stephen Hawking
• Zero - Cherles Seife
• Neutrino - Frank Close
•
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